Cassidy and his team published the largest and most thorough research study on this issue. The leading research study on this came out of Ontario in 2008. I know what you’re thinking – that is quite a while ago. Surely there is more recent information out there. You’re right, but here’s the thing. Many authors have tried to study this subject again, but all keep coming back to the same conclusions these authors found back in 2008. So let’s look at what they figured out.
The tough part about this question is that, while there have been reported cases of stroke in a very small number of people suffering a stroke within a very short time (or even immediately) following having their neck manipulated. The challenge is that it has happened so rarely, it is almost impossible to study because there are so few occurrences. To address this, these authors took a very unique approach.
They studied all Ontario hospital admissions of patients for Verbrobasilar Artery (VBA) Stroke from 1993 to 2002. This resulted in 100 million person-years worth of data (number of people multiplied by their age). This is somewhat mindblowing and hard to wrap your head around numbers this big but that is how much data these authors studied. For fun, here’s how many zeros that is: 100,000,000 😳 😱
FUN ANATOMY FACT: The Vertebral arteries (there are two of them) are small arteries that travel up through the neck and take a hard turn at the top to enter the skull. They join together at the base of the skull to form the vertebrobasilar artery (VBA), also referred to as the vertebrobasilar system. They supply blood to the back part of the brain. These two arteries are thought to be the culprits that get injured during neck treatments. BTW, they are also the ones associated with strokes involved with other things that strain your neck such as car accidents, sports trauma and other neck injuries. They are also at risk from underlying lifestyle-related issues such as arteriosclerosis (hardening of the arteries). Other things that increase your risk to stroke include things like being on blood thinners or birth control medication.
This huge population-based study concluded that there was no increased risk of suffering a stroke from chiropractic treatment. The really interesting thing about this study was that there was an increased incidence of stroke in those admitted to the hospital for stroke in those that had previously seen their family doctor and/or a chiropractor prior to having the stroke. The authors concluded that this higher incidence did not mean that the family doctor or the chiropractor caused the stroke, but rather the patients were seeking care for early-stage stroke symptoms from those care providers.
You see, in the early stages, this type of stroke typically causes neck pain and headaches. So it appears that patients would be experiencing neck pain and headaches and seek care from either the chiro or their GP but then go on and have a stroke. The treatment the chiro or GP didn’t actually cause the stroke. Because they were in such an early stage of stroke, the practitioner did not pick up on it and treated the neck pain and headache as a normal muscle-tension or sprain/strain type of problem. The GP likely recommended medication and the chiro likely adjusted (manipulated) the neck and upper back and massaged the muscles. The stroke continued to progress and the poor person then had to go to the emergency department. Once at the hospital, they would be asked what they did leading up to having the stroke and if they said they went to a chiro, that would be noted in the chart. Where things went sideways and incorrect conclusions were drawn, was the leap in logic that if they went to the chiro and then had the stroke, it must have been the chiro treatment that caused it.
That is until Dr. Cassidy and his team took a look and figured out the error in this logic. If there was no difference between those that saw the GP vs those that saw the chiro, then it is pretty hard to claim that the chiro treatment causes strokes. If you follow that logic, then you would have to also acknowledge that the treatment the GP did (recommending meds) also caused the stroke. Perhaps, but unlikely. Remember that next time you are reaching for the pain killers, anti-inflammatories or muscle relaxants.
Turns out, it is a temporal relationship rather than a causal one. That means something happens related to something else by the timeframe. So imagine if you fed your dog within a few hours of having a stroke. It seems kind of silly to conclude that feeding a dog could cause a stroke but there you have it. Same logic.
But you have heard that people have had a stroke after getting their neck cracked. What’s up with that?
You bet, it has been reported that this happens. How often and how does this compare to other things people commonly do when trying to relieve their neck pain and headaches?
Here is how the risk stacks up against other common medical treatments for neck pain:
- Chiro (neck manipulation): 1 stroke death per million people
- NSAID’s (Over-the-counter pain relievers such as tylenol and advil): 153 stroke deaths per million people
- Narcotic medications (Opiods): 53 stroke deaths per million people
- Spinal surgery for neck pain: 500 stroke deaths per million people
Bottom Line: People who are in the early stages of VBA-type stroke will present with neck pain and headaches. They often go see their family doctor or a chiropractor for help. Because they are in such an early stage of stroke, it is possible that the practitioner does not pick up on it and treats it as a normal neck strain +/- muscle tension-type headache. Unfortunately, the person goes on to have a stroke and then mistakingly, the stroke gets blamed on the treatment given by the chiropractor or the family doctor.
What should you do?
Don’t let fear of the unknown prevent you from seeking care as there are potentially significant benefits. Get the facts sorted and make an informed decision.
Yes, there can be risks with any treatment you seek, whether that is reaching for the bottle of painkillers or seeing a chiropractor. If your chiropractor is recommending neck adjustments but you are worried about the risks, make sure that discussion occurs BEFORE any treatment occurs. If, after discussing the risks, you decide you still aren’t comfortable with neck adjustments, remember that there are other treatments your chiropractor should be able to offer. Modern chiros are no longer one-trick ponies and there is good evidence out there that shows other treatment approaches can be helpful. Make sure to discuss these with your chiro.
On the off-chance your neck pain and headaches are an early warning sign of a major health problem such as stroke, know what to look for. Here are the classic signs of stroke: F.A.S.T:
Face Drooping: Is one side of your face drooping or numb? Look in the mirror and smile – Is your smile uneven?
Arm Weakness: Is one of your arms weak or numb? Raise your arms above your head. Does one of your arms drift downwards?
Speech difficulty: Is your speech slurred?
Time: Time to call 911!
I hope this helps. As always, if you have any questions or concerns or need some clarification, feel free to reach out directly to me.